Intrinsic Wave Impedance for Conductive Medium

1. The problem statement, all variables and given/known data
I know that for air, the intrinsic impedance η is 377 Ω, but it becomes complex in a conductive medium. This fact is sort of hindering me in being able to answer a few problems consisting of electric and magnetic waves in a conductive medium, but I just wanted to clarify one thing.
Say, I am given H(z,t)=0.5cos(ωt-βz)ay+0.7cos(ωt-βz)ax

2. Relevant equations
I know that the intrinsic impedance for a conductive medium is:

3. The attempt at a solution
When σ=0 for one problem, I was left with:
But I do know that

My question is, what in the world is u_o, ε_o, and ε_r ???
Am I supposed to figure this out or is this already provided in a table somewhere?
I have been trying to look in my book and online, but am getting confused easily.
Will someone please clarify this for me?
Any help is greatly appreciated!

Those are all real constants. mu_0 and epsilon_0 are permeability and permittivity of free space, look them up anywhere, and epsilon_r is the relative permittivity of your medium (= epsilon/epsilon_0).

How you got as far as you did, which is pretty far, without knowing that is a bit of a mysrtery to me, and please believe that I'm nort trying to be condescending or insulting - just wondering!